Polarised magnetostatic relay



Sept. 12, 1961 P. BURSTOW POLARISED MAGNETOSTATIC RELAY 2 Sheets-Sheet 1 Filed Feb. 2, 1959 k c N I z T m B llllll IIC W 2 0 "l FL... m. N

3 W F .k c N I 1| 0 m5 F1 L L c N w WVENTUR A 7777(IVE) Sept. 12, 1961 Filed Feb. 2, 1959 P. BU RSTOW POLARISED MAGNETOSTATIC RELAY 2 Sheets-Sheet 2 nvvzurok F/EKAE auesrow A Tram/v5) United StatsPatent 2,999,946 POLARISED MAGNETOSTATI'C RELAY Pierre Burstow, Paris, France, assignor to Compagnie Industrielle des Telephones, Paris, France, a corporation of France Filed Feb. 2, 1959, Ser. No. 790,602 Claims priority, application France Feb. 13, 1958 7 Claims. (Cl. 307-88) The present invention concerns control and storage devices which can be used more especially in automatic telephony and remote control. There is already known, more especially from applicants 'French patent application, Magnetostatic relay, dated November 9, 1956, a magnetostatic relay with or without storage properties, which is based upon the association of a special magnetic amplifier arrangement with a transistor, the relay being such that the output current is zero (relay inoperative) when the control ampere-turns are below a certain value and that the output current assumes a constant value different from zero (relay operative) when the control ampere-turns are above the said value, the change from the zero value to the constant .value taking place without passing through intermediate values. This ampere-turns value at which the output current changes from the zero value to, a finite value is that at which, the relay is operated. In the case of a relay having no storage prop cities, the output current is restored to zero when the ampere-turns, in decreasing, again pass through the value ,at which the relay was operated. In the case of a storage relay, the output current is restored to zero at a control ampere-turns value lower than that at which the relay wasoperated, this return to the inoperative state taking place without passing through intermediate values. Such types of relays are called bistable.

, It is also known in the electromagnetic relay art that some relays, called polarised relays, have one inoperative position and two operative positions. The central inoperative position corresponds, for example, to no contact closed, one of the operative positions corresponds to a left-hand contact closed and the other operative position corresponds to a right-hand contact closed. This permits the location of a mid-point either on the right-hand contact or' on the left-hand contact, each representing, for example, a source of current of diiferent nature, and the relay when in the inoperative state having balanced polarisation and being capable of changing over either to the left or to the right, in accordance with the direction of the control current.

A magnetostatic relay having three positions affording similar possibilities to the polarised electro-magnetic ice back ampere-turns, the said collector being connected by two branches through rectifiers to two direct-current sources of appropriate polarities so as to render one or both of the branches non-conductive for alternating current in accordance with the potential of the collector, and

the said collector being connected to a direct-current inoperative state and two symmetrical operative states.

Such an output curve of the relay isobtained byapply ing negative feedback ampere-turns to a magnetostatic relay.

In the case of a relay in which the transistor is of the p-n-p-type, it is known that the current in the collector substantially follows the variation of the current relay'cannot be designed with the known current curve.

It is necessary that the curve in accordance with which the output current of such a relay is set up as a. function of the control ampere-turns should not change from the zero value to a finite value without assuming intermediate values, as does the bistable relay. Inother words, the curve representing the setting-up of the current as a function of the ampere-turns must have a certain slope, of which the two extreme values corresponds to the two operative positions and of which the mid-value locates the inoperative position, the latter being defined by zero control ampere-turns.

The present invention has for its object to provide a polarised magnetostatic relay having three positions: one inoperative position and two operative positions, which are defined in the aforesaid manner.

The relay according to the invention is characterised by the fact that it comprises a feedback winding wound on the saturable magnetic circuit of the magnetic ampliher and introduced into the circuit of the collector of the'transistor in such manner as to supply negative feedin the emitter as long as the voltage of the collector remains lower than that of the base, and consequently it Will be easy, by tracing the network of curves I (col; lector current) as a function of V, (collector voltage for values of I equal to the normal output currentl, to half the current and to a zero current 1 :0, to determine the corresponding intermediate values of V Therefore, V cantake various values according to the current supplied, that is to say, according to the control ampere-turns applied to the relay.

The collector of the magnetostatic relay is connected by two branches through oppositely directed rectifiers to two appropriately chosen polarities so as to render one or both of the two branches non-conductive.

The collector is separated from the point common to the two branches by a filtering inductance and the said common point is connected through a condenser to an inductive circuit, for example to the winding of a trans former. If each of the branches is connected to a different alternating-current source as well as to potentials of different polarities, each branch may be conductive for one of the alternating currents in accordance with the control ampere-turns applied to the relay.

Further features and advantages of the invention will become apparent from the description hereinafter given with reference to the figures of the accompanying drawings, which show by way of example one constructional form of the relay according to the invention:

FIGURE 1 shows the output current of a magnetostatic relay of known type having no feedback. Q

FIGURE 2 shows the output current of a relay according to the invention with negative feedback.

FIGURE 3 shows the circuit diagram of a magnetostatic relay with negative feedback.

FIGURE 4 shows the curve V as a function of 1,, for different values of I FIGURE 5 shows the circuit diagram of the relay with a common point and the two branches at certain potentials.

FIGURE 6 shows the complete circuit diagram of the relay according to the invention.

FIGURE 1 shows the curve of the output current in a magnetostatic relay of known type having no feedback.

"It will be seen that at a certain control ampere-turns value' (N IQ the output current passes through a zero value at a constant value I. Such a type of relay can ri r therefore only be in two difierent states: one inoperative state with zero output current, the number of control ampere-turns being lower than (N IQ and one operative state with a constant output current value I, the number of control ampere-turns being higher than c c)T- FIGURE 2 shows the curve of the output current of a magnetostatic relay in which the output current ceases to be zero at a certain number of control ampere-turns (N IQ but assumes its constant value I only at another control ampere-turns value (N IQ the difierence between these two values being variable. For a certain range of values of control ampere-turns, the curve of the current therefore has a sloping portion, the slope of which depends upon the influence of the negative feedback winding on the control windings, the degree of feedback being defined by:

N tan aim- N being the number of turns of the feedback winding and N being the number of turns of the control winding.

It is obvious that according to whether the ratio N/N' is smaller than, equal to or greater than 1, the angle a is smaller than, equal to or greater than 45.

FIGURE 3 shows the circuit diagram of such a relay, which differs from the normal magnetostatic relay only in that the feedback winding III, which is used by reversal of its terminals E and S, gives negative ampereturns.

The relay thus illustrated in FIGURE 3 comprises a saturable magnetic core on which are wound a control winding 1, an operating winding II, a feedback winding III and a bias winding IV. A rectifier R is connected in series with the operating winding II and a transistor T is connected to the output of the rectifier R A resistance r is connected on the one hand to the emitter e of the transistor T and on the other hand to a directcurrent source of negative voltage U The collector C of the transistor T is connected to one end F of a load resistance R through the feedback winding III, the base b of the transistor T is connected to a direct-current source of negative voltatge U and'a condenser C,, is connected between the collector C and the base b of the transistor T The load impedance R is connected on the other hand to a direct-current source of negative voltage -U Considering, in this relay, the point F whose potential is very substantially the same as that of the point D of the collector (the resistance of the winding III being low in relation to the load resistance Re), it will be seen that the potential of the point P varies in accordance with the output of the relay. The potential of the point F is obviously equal to -U if the output current of the relay is zero. It is substantially zero if the output current of the relay is equal to I.

. FIGURE 4 permits of extending these results, and indicates the current I in the collector of the transistor T as a function of the negative potential V of the collector. Assuming, for example, that the collector is at the potential --40 volts in the inoperative state, the load line CH is traced, the collector supplying a current I for V =0. This line intersects the curve of the current 1/2 at a point T which corresponds to a collector potential of -20 volts.

The following results can thus be written: For I =0 V =--40 For I,,=I/ 2 V 20 P01 1 7 V =0 It will be seen that the potential of the point F, which is substantially the same as the potential V of the collector, varies in accordance with the output of the relay. FIGURE illustrates a blocking and deblocking de-- vice depending upon the potential of the point F. The point F is connected by two branches to two points G 4 and H, the connection FG being made across a rectifier R oriented with its forward direction f from G towards F and the connection FH across a rectifier R of opposite forward direction 73. The point G is connected to a negative potential U which is lower than the potential of the point F for the inoperative current 1/2 designated by U F I and the point H is connected to a negative potential U;,

which is higher than that of the point F for the inoperative current 1/2. Also, --U must be lower than -U We therefore have:

Under these conditions, if we take, for example --U -3O and -U ==10, the point F being at the potential -20 in the inoperative state, the rectifier R will not be conductive, nor will the rectifier R which is of opposite direction. However, if the point F takes the potential 0 (relay supplying the current I), the rectifier R will be conductive in the direction f2 (the potential of F being higher than that of H) and the rectifier R is non-conductive.

If the point P takes the potential 40, the rectifier R becomes conductive in the direction f1 and the rectifier R is non-conductive.

It will therefore be seen that in accordance with the potential of the point F, the two branches PG and PH can be simultaneously non-conductive, that the branch FG alone can be non-conductive or that the branch FG alone can be non-conductive. A winding in series with R or R would therefore be capable of having or not having a current passed therethrough.

FIGURE 6 shows the complete circuit diagram of the relay according to the invention. Connected between the point F of the collector and the point L common to the two branches LA and LB is a filtering inductance La. One end of the inductance La is also connected to a condenser C the other electrode of the condenser being connected to a winding of a transformer Ta, whose other end is at a certain polarity. A utilisation circuit U! is connected between the terminals of the secondary wind- The point A is connected to one of the poles of an alternating-current source 00, for example to the engaged alternating-current source, while the other pole of the said source is connected to the point A which is in turn connected to the negative terminal U of a direct-current source.

The point B is connected to one of the poles of another alternating-current source AP, for example to the ringing alternating-current source, while the other pole of the said source is connected to the point B2, which is in turn connected to the negative terminal U of a directcurrent source.

The point A is connected to the point L through the rectifier R oriented with its forward direction as indicated by the arrow f1, and the point B is connected to the point L through the rectifier R which is oriented with its forward direction as indicated by the arrow f2 in the opposite direction to R The load resistance R is connected to a negative po tential U If the potential of the point F is designated by when the collector of the transistor Tr supplies a current 1/2, i.e. when the relay is in the inoperative position,

a sists the values of the various potentials must satisfy the relation:

UM U1 UF 1 U2 These conditions are satisfied, and the device operates in the following manner; assuming that the ringing current or the holding current is to be sent to a subscriber and that the numerical values are as follows:

potentialof'E -40). The holding current will therefore flow through the branch A; R L and will go to the primary winding of the transformer T through the condenser C,,, the inductance L, forming an obstacle thereto, while the condenser C ofiers only a low impedance thereto. The secondary winding therefore has a holding current in its utilisation circuit Ut.

When the relay supplies its normal current I, the potential of the point F becomes equal to 0. In this case, the rectifier R is conductive in the direction of the arrow 2 since the potential of F (zero) is higher than the potential of B The ringing current will therefore flow through the branch B R L and will -go to the primary winding of the transformer T, similarly to the holding current.

These two states of the relay correspond to its two operate positions, its inoperative position being defined for an output current equal to 1/2, and the control ampere-turns being zero. In the inoperative position, the potential of the point F is equal to 20, and at this value none of the rectifiers R and R is conductive. Ringing current is therefore sent when the output current of the relay is equal to I and the sending of this current is stopped when the output current of the relay is equal to 1/2. Holding current is sent when the output current 'of the relay is equal to zero and stopped when the output current of the relay is equal to 1/2.

Therefore, such a relay performs the function of a three-position reversing switch. In its inoperative position, in which the two branches are blocked, there is a polarising current 1/2 at the collector, which maintains the potential of the collector at half the value of the maximum polarising voltage U of the collector. It is in this sense that it can be called a polarised relay.

In one of the two change-over positions, one of the branches is blocked and the other is conductive, and this state is produced, for example, when the current at the collector is zero, that is to say, when the voltage at the collector is V U In the other change-over position, with the constant current I at the collector, there is a reversal: the branch which was non-conductive becomes conductive and that which was conductive becomes nonconductive. In this case, there is a voltage at the collector V =0.

This relay has been described on the assumption that the transistor is of the p-n-p-type, but it is obvious that a transistor of the n-p-n-type could be used by appropriately adapting the polarities.

In the described example, the relay according to the invention is used for sending the ringing or holding current to a subscriber, but it is obvious that it may be employed for the alternate application of two alternating currents from difierent sources or two direct-currents at different voltages.

I claim:

1. Polarised magnetostatic relay having three stable operating states, comprising a magnetic amplifier including a saturable magnetic circuit on which are wound at least one power winding, one control winding, one bias and one feedback winding, and a transistor connected into the circuit of the power winding of the magnetic amplifier, the feedback winding being connected into the circuit of a collector of the transistor in such manner as to produce negative feedback ampere-turns, the said collector being thereafter connected on the one hand to a direct-current source through a load impedance, and on the other hand by two branches, each branch including a rectifier and an alternating-current source, to appropriate respective direct-current sources, so as to render one or both of the branches non-conductive for the said alternating currents, depending upon the potential of the collector, the said potential taking only the value zero and two values of like polarity.

2. Relay according to claim 1, wherein an inductance is connected between the collector of the transistor and a point common to the two aforesaid branches, one of the branches being connected to a direct-current source through a rectifier and a first alternating-current source, the other branch being connected to another direct-current source through a rectifier of opposite direction to the preceding rectifier and a second alternating-current source, and the point common to the two branches also being connected through a condenser to an inductive winding for the transmission of the alternating-current from one of the two alternatingscurrent sources.

3. Relay according to claim 1, wherein the number of turns of the feedback winding is so chosen as to determine two values of control ampere-turns between which the current in the load of the relay increases along a curve in proportion to the control ampere-turns from a minimum constant value to a maximum constant value, and outside which the current in the load of the relay takes the minimum constant value or the maximum constant value, the mid-point of that portion of the curve in which the load current is proportional to the ampereturns corresponding to zero control ampere-turns and to a load current equal to half the maximum constant current, the values thus defined corresponding to three stable operating states of the relay, one inoperative state corresponding to a zero control ampere-turns value and to a load current equal to half the maximum output current of one of the operative states, a first operative state corresponding to the minimum output current and a second operative state corresponding to the maximum output current.

4. Relay according to claim 1, wherein the two branches connected to the collector of the transistor are simultaneously rendered non-conductive when the load current is equal to half the maximum constant current, one of the branches being conductive for a direct current provided by the polarity of the respective directcurrent source of this branch and the other being nonconductive when the load current is zero and, conversely, said last-mentioned one branch becoming non-conductive while the other branch which was non-conductive becomes conductive for the direct current provided by the polarity of the respective direct-current source of the second branch when the load current is equal to the maximum constant current.

5. Relay according to claim 1, wherein the rectifier of the first branch is oriented with its forward direction towards the collector circuit, and the rectifier of the other branch is oriented with its forward direction opposite thereto, the two branches allowing no alternating current to pass when the load current is equal to half the maximum current, one of the branches allowing the passage of the alternating current from the first alternatingcurrent source and of the superimposed direct current from the first branch direct-current source when the load current is zero, the other branch allowing the passage of the alternating current from the second alternating current source and of the superimposed direct current from the second branch direct current source when the load current is equal to the maximum constant current.

6. A polarized magnetos'taticrelay having three-stable goperating states, comprising a magnetic amplifier including a saturable magnetic circuit with an operating winding wound thereon and a plurality of further windings wound thereon including at least a control winding and a feedback winding, a transistor connected in circuit with the operating winding and including a collector electrode, said collector electrode being connected in a circuit including said feedback winding and a load impedance with the collector current providing negative feedback ampereturns at said feedback winding, a pair of branch circuits connected to said collector circuit between the collector and said load impedance, each branch circuit including a rectifier and a respective direct-current source, each said direct-current source providing a potential in the respective branch circuit whereby each of said branch circuits may selectively be made conducting our non-conducting .to direct-current, depending upon. the potential of the collector which is determined by the total control ampere-turns of said further windings, andmeans connected to said branch circuits for utilizing the changes in direct-currents therein.

7. A magnetostatic relay according to claim 6, wherein the rectifiers in said branch circuits are connected in opposition ,and wherein the direct-current sources of said branch circuits have such potential and polarity that only one or the other or neither of said branch circuits is conducting, depending upon the control ampere-turns of said control winding, corresponding to the three stable operating states of the relay.

References Cited in the file of this patent UNITED STATES PATENTS 2,909,674 Moore et a1. Oct. 20, 1959 

